1. Field of the Invention
This invention relates to the field of storage servers. In particular, the invention relates to servers and function used for intelligent storage area networks.
2. Description of the Related Art
Technologies for data storage can be described as based on three commonly used methods: local storage, server based, and small computer system interfaces (SCSI) based.
Local storage means that the information is stored directly on the local machine. An example would be the attached hard disk on an IBM PC, or compatible. In contrast, server storage means that the information is located on one or more servers. The server has responsibility for storing the information as well as computing and processing requests based on the information. SCSI solutions are based on a bus architecture for server to storage connectivity.
These solutions have several limitations. Most of these solutions suffer from insufficient bandwidth. For example, in the network server environment, the same local area network (LAN) may need to be shared for tasks such as backup and regular data access. A second limitation is that existing server technologies can suffer from data availability problems due to server downtime. A third limitation is that the current storage technologies do not scale well as an organizations storage capacity needs grow. A fourth limitation is that when data storage and processing transactions reside in the same location it can be difficult to optimally divide resources between the two tasks.
A storage area network (SAN) can offer solutions to many of these limitations. A SAN can permit multiple servers to access the stored data simultaneously. A SAN typically uses high speed connections such as fibre channel arbitrated loops (FC-AL) to interconnect the storage devices to the servers. Additionally, LAN based PC technologies for storage can have high costs on the order of several hundred thousand dollars per due to storage management costs for file management labor and for lost productivity from downtime.
A SAN reduces server and network downtime. A SAN centralizes storage repositories such as backups, archiving, and disk mirroring and reduces administrative costs. The result is an environment with centralized management but distributed network functionality.
However, prior storage area network server architectures often rely on expensive, nonstandard components, and remain difficult to administer.
A storage server according to the present invention comprises a processing unit, a bus system coupled to the processing unit, a communication interface, and an operating system coupled to the processing unit. The bus system has slots that are adapted to hold interfaces to data stores, located either on the server chassis or across communication channels coupled to the slots. The operating system provides logic for controlling transfers over the bus system. The operating system provides logic for translating storage transactions received over the communication interface from client servers into an internal format. The operating system provides logic for processing the internal format according to configuration data that maps a storage transaction on the communication interfaces for a particular unit of storage within the extent of the protocol of the transaction to a virtual circuit corresponding to that extent using the internal format. The virtual circuit in turn manages routing of the transaction to one or more physical data stores through one or more drivers in the interfaces. Also, the server includes resources to emulate physical storage devices, so that client servers are able to use standard storage transaction protocols for access to the virtual devices without changes in configuration of the client server for storage transaction.
In one embodiment, the storage server comprises a communication interface. The communication interface supports a storage transaction communication channel. The storage server includes logic for translating a storage transaction received over the communication channel to an internal format. In one embodiment, a standard xe2x80x9cintelligent input/output block storage architecturexe2x80x9d (I2O BSA) message format is used as the internal format. The storage server includes logic for routing the storage transaction in the internal format to a virtual circuit. The virtual circuit manages connections to data stores in communication with the storage server including connections to physical storage device and connections to virtual devices directed by other storage servers.
According to another aspect of the invention, a storage router is provided. The storage router includes a first communication interface, other communication interfaces, a processing unit, and a bus system. The bus system is coupled with the processing unit, the first communication interface, and the other communication interfaces. The processing unit supports an operating system. The operating system directs storage transactions received over the first communication interface to appropriate other communication interfaces according to configuration data, using the virtual device architecture and emulation.
In some embodiments, the communication interface is an interface to a fibre optic medium. In some embodiments, the communication interface includes drivers compliant with a fibre channel arbitrated loop. In some embodiments the communication interface includes drivers compliant with the standard xe2x80x9csmall computer system interface version 3xe2x80x9d (SCSI-3).
In some embodiments, the processing unit is comprised of a plurality of processing units.
In some embodiments, the bus system is comprised of interconnected computer buses. In some embodiments, the computer buses are compliant with a standard xe2x80x9cperipheral component interconnectxe2x80x9d (PCI) bus. In some embodiments, the communications interface is coupled to the bus system.
In some embodiments, the storage server includes nonvolatile storage. In some embodiments, the nonvolatile storage comprises integrated circuit non-volatile memory, such as flash memory.
In some embodiments, the storage server includes controllers for a disk drive. In some embodiments, the controller supports an array of disk drives. In some embodiments, the controller supports a standard xe2x80x9credundant arrays of independent disksxe2x80x9d (RAID) protocol. In some embodiments, the disk drives are coupled to the controllers by a fibre optic medium. In some embodiments, the disk drives have dual interfaces for connecting to a fibre optic medium. In some embodiments, each disk drive is coupled to at least two controllers.
In some embodiments, the operating system includes logic for translating SCSI-3 instructions and data received over the communication interface into an internal format. In some embodiments, the logical unit number (LUN) associated with the SCSI-3 instructions is used to associate the SCSI-3 instructions and data with virtual devices including data stores in the storage server. In some embodiments, the initiator SCSI-3 identification number (ID) and the LUN are used to associate the SCSI-3 instructions and data with virtual devices including data sources coupled to the storage server.
In some embodiments, the operating system includes logic to monitor the performance and condition of the storage server. In some embodiments, there is logic for handling device failures and transferring control to redundant components.
The present invention provides an intelligent storage routing device managing logical and physical access to a pool of shared storage devices. The device is logically closer to the client server than to the storage devices, responds to client specific requests for storage transactions required for accessing and sharing a storage area network coupled to device. The device manages the use of a cache memory to enhance performance, fundamentally the device facilitates on the device in a preferred system access by client servers to their storage. Key functions provided at the device include authentication and access permission logic, virtual device mapping, storage mirror functions, and a large nonvolatile cache. With these basic functions many powerful storage management applications can be implemented with existing servers and storage devices, and the addition of new storage to networks is facilitated.